I think they describe the operation in one of the scans on Larry's site, but here's a text version for ya Kurt. There's no danger with the South-wind, as they only burn under a vacuum. They're a pretty neat item, and make allot of heat, about 40,000 btus on high.
The heater exhaust, is connected to the engine intake manifold, the engine vacuum is what "drives" the heater combustion.
The heater draws gasoline from the carb bowl, through a tiny tube, just outside the carb, there is a "jet assembly" where the gasoline is mixed with air, so it is a vapour passing through the heater fuel line, and not just gasoline. At the back of the heater, there is another place where the fuel is mixed with air (also an automatic choke controlled by a bi-metallic strip). The fuel and air mixture (14.7 to 1) then goes into the "oven" where it combusts. There is an electric ignitor in the oven, sort of like a model airplane glow plug. From here, the exhaust gasses are pulled into the engine intake manifold.
If there is a loss of vacuum for any reason, like a line leaking, or you floor it, the heater just goes out. The heater can instantly re-ignite after 15 seconds of no vacuum, but after that time, it cools down, then automatically relights. There is also an automatically reseting overheat shut down as well.
To use the heater, you start the vehicle engine, then pull out the knob. The engine speeds up for a few seconds, as it gets a tiny amount more fuel and air, then slows back down as the heater ignites. This takes about 10 seconds or so. After about 90 seconds, the heater fan starts up, and then in about another 30 or so, the ignitor shuts off.
The operation of the heater is controlled by two sets of points, and three bimetallic strips, one that operates the automatic choke, and the other the points, which controls the ignitor and the fan.
On high, the air coming out of the heater is about 90 Celsius or so, and on low its about 60 Celsius. On low, the heater just gets less vacuum.
I believe that the heater only burns about 250 ml of fuel per hour, so you can't actually detect it when calculating fuel mileage.
After you shut the heater down, the fan stays on until the heater cools down, and then cycles on and off a few times as well, to cool the heater down.
What's funny, is when you restart the heater before it has completely cooled down, is that the fan will come on instantly, and starts blowing heat until the heater cools down enough that the ignitor re-ignites the oven.
I love my heater. I have delightful hot heat, before I'm backed out of the driveway, and my whole uninsulated bus is comfortable.
